The 2p rise in fuel duty, due to come into force in October, is likely to be deferred, the chancellor, Alistair Darling, said yesterday as he acknowledged the pressures of rising petrol prices on families and business.

In an attempt to clarify the government position on fuel and car taxes, amid reports of a second tax U-turn in less than a month, after that on the 10p rate, Darling said he would make a final decision on the 2p increase by early autumn.

"I intend to come back to the issue of the fuel tax increase that would be due this October," he told Radio 4's The World at One. "I will do that, because I am very conscious of the fact that people are concerned about the amount of money they are now having to pay out every time they have to fill up their car."

His announcement came as he and Gordon Brown showed their determination to deal with rising oil prices and the importance of improving the security of Britain's energy supplies by making two key announcements. During a meeting with oil industry executives in Banchory, near Aberdeen, the prime minister:

· Made clear the government would press ahead with a new generation of nuclear power stations, declaring for the first time that new sites could be found. "We want to do more to diversify our supply of energy and that's why I think we are pretty clear that we will have to do more than simply replace existing nuclear capability in Britain. We will be more ambitious for our plans for nuclear in the future." His remarks echoed those by the business secretary, John Hutton, in March.

· Pledged to boost the production of oil by lending the government's support to increasing North Sea exploration. Darling admitted that boosting UK oil production would have a negligible impact on the international price of a barrel.

While the two initiatives will have little impact in the medium term, Downing Street hoped to send a clear signal that the prime minister is aware of the impact of rising fuel prices and is taking action.

Darling said the government had two priorities: to try to drive down oil prices by joining with other countries to persuade Opec to increase production, and to examine fuel taxes in Britain.

There was confusion about the government's plans on fuel and car taxes on Tuesday. Jack Straw, the justice secretary, and John Hutton, the business secretary, gave the impression that there could be movement on the fuel duty and a second measure, the £200 increase in car tax for polluting cars bought since 2001. Downing Street played down the significance of their remarks on Tuesday night when it said no changes were being examined.

Darling attempted to clarify the government's intentions by indicating that the fuel duty increase, which was deferred in March's budget, would be postponed again in October. The chancellor would probably review the increase again in next year's budget, a move that would deprive the Treasury of £555m.

The chancellor was less forthcoming on the increase in car tax on polluting vehicles. He dismissed criticisms made by Greenpeace that it gave green taxes a bad name because it would apply retrospectively and therefore not achieve the government's stated intention for such taxes: to change people's future behaviour. "The VED [vehicle excise duty] has been linked to how polluting a car is since the beginning of the decade," he said.